Using the energy of quantum oscillations

I read somewhere that, due to quantum fluctuations, there is enough energy in one cubic centimeter to boil the planet's oceans. Is this true? If so, could such energy be harnessed? Or is there some fundamental limit?

Suppose some quantum mechanical system has two possible energy levels: 10^(10000)J and 10^(10000)J+1eV. How big quanta of energy would you expect ever to be emitted out of this system? The correct answer is, that only quanta of 1eV. It doesn't matter how high the ground state is, it is still the ground state, and you cannot make the energy of system any smaller.

The zero-point energy of the quantum fields is large, but it is still the ground state energy, and it cannot be taken out of the field.